Something I don't hear enough about on most threads or conversations about carbs is this: A bigger carb will produce more horsepower, but it always does it at higher rpm's. In other words, the bigger the carb, the faster you have to spin the motor to access the added horsepower. With a relatively stock motor a 500 cfm carb is probably not the best bet. Here's an example. A stock 250 with no changes except a glasspack and a Holley/Weber 5200 will float the valves in first and second with both a saginaw or a muncie 3 speed. So with a carb that's only 270 cfm when measured by 2 barrel standards will turn the engine high enough to run out of camshaft before you run out of carburetion ability. On a set up like we're talking about here I would go with the 390 Holley or else a pair of carter YF or weber carbs. The 500 cfm edlebrock may be okay, but CERTAINLY nothing any bigger. That's just my opinion anyway.
Boo
